EDWARDS AIR FORCE BASE, Calif -- The Dryden Flight Research Center conducted its first test of a solid-fueled rocket with an aerospike engine. The radical missile utilized its own shock wave to shape and direct its exhaust plume, thereby achieving much greater efficiencies in flight than a conventional bell-shaped nozzle. The ten-foot long missile was launched in West Texas and achieved Mach 1.5, reaching 26,000 ft. It was the first time that flight data was acquired from an aerospike rocket in flight.
The aerospike engine is a type of rocket engine that maintains its aerodynamic efficiency across a wide range of altitudes. It belongs to the class of altitude compensating nozzle engines. A vehicle with an aerospike engine uses 25–30 percent less fuel at low altitudes, where most missions have the greatest need for thrust. Aerospike engines have been studied for a number of years and are the baseline engines for many single-stage-to-orbit (SSTO) designs and were also a strong contender for the Space Shuttle main engine. However, no such engine is in commercial production, although some large-scale aerospikes are in testing phases. The terminology in the literature surrounding this subject is somewhat confused—the term aerospike was originally used for a truncated plug nozzle with a very rough conical taper and some gas injection, forming an "air spike" to help make up for the absence of the plug tail. However, frequently, a full-length plug nozzle is now called an aerospike.